Problem matching "Contents" in iCloud Files

I have a Rule matching "Contents contain #Event" in Textfiles in iCloud.
This Rule stopped working after updating to Monterey.
While Previewing the Rule clicking on the Red X dows not show any Content in the File.
Spotlight is indexing the file including it's content.

If you search for #Event in Spotlight, you are saying the file in question shows up in the results? Is #Event in the filename or just the content?

Yes. #Event is only in the content of the Textfile.
I just found out, that the behavior is inconsistent. Today it moved some older files. But newer files are still there, the indicator is red (when previewing the rule) and I can find them with spotlight.

Can you post an image of the preview?